2008 Volume 19 Issue 1

Synthesis of derivatives of imidazo[4,5-b] pyridine: Novel sulfur contained side chains for macrolide antibiotics
Lu Liu , Peng Xu , Liang Zhou , Ping Sheng Lei
2008, 19(1): 1-4  doi: 10.1016/j.cclet.2007.11.012
[Abstract](168) [FullText HTML] [PDF 261KB](0)
Abstract:
Two series of novel derivatives of imidazo[4,5-b]pyridine were synthesized. These compounds could be used as side chains of semisynthesised ketolide antibiotics. The side chains have free amine group which can attached to ketolide core. Macrolides with this kind of side chains will show obvious activities against erythromycin-resistant strains. The structure of the side chains was confirmed by 1H, 13C NMR, MS, HMBC spectra.
One-pot synthesis, antibacterial and antifungal activities of novel 2,5-disubstituted-1,3,4-oxadiazoles
Abdul Rauf , Shweta Sharma , Saloni Gangal
2008, 19(1): 5-8  doi: 10.1016/j.cclet.2007.11.026
[Abstract](169) [FullText HTML] [PDF 263KB](0)
Abstract:
A series of novel 2,5-disubstituted-1,3A-oxadiazoles have been synthesized from long-chain alkanoie and alkenoic acids. The structures of these compounds have been elucidated by elemental and spectral (IR, 1H NMR, 13C NMR, MS) analysis. Furthermore, compounds were screened for in vitro antibacterial activity against the representative panel of two Gram-positive and two Gram-negative bacteria. All the synthesized compounds were also tested for their inhibitory action against five strains of fungus. The various compounds show potent inhibitory action against test organisms.
Synthesis of novel biscalixarene-tube containing two kinds of calix[4]arene derivative units
Fa Fu Yang , Li Ming Liu , Chao Hui Liu , Xiao Hua Zheng , Yu Guo
2008, 19(1): 9-11  doi: 10.1016/j.cclet.2007.10.032
[Abstract](161) [FullText HTML] [PDF 271KB](0)
Abstract:
A novel biscalixarene with two kinds of calix[4]arene derivative units connected by four bridging chains, was facilely synthesized by "1+1" condensation mode in high yield. The element analyses, ESI-MS, 1H NMR and 1H-1H COSY spectrum showed that the calix[4]arene units of compound 4 were in cone conformations and compound 4 possessed biscalixarene-tube structure.
Convenient synthesis of some optically active 1,4-benzodiazepin-2,5-diones
M. Bakavoli , A. Davoodnia , R. Shahnaee
2008, 19(1): 12-14  doi: 10.1016/j.cclet.2007.10.043
[Abstract](160) [FullText HTML] [PDF 243KB](0)
Abstract:
Isatoic anhydride was reacted with several L-amino acids to give the corresponding (2S)-N-(o-aminobenzoyl)-2-alkyl-aminoacetic acids. The latter compounds were treated with phosphoryl chloride under reflux temperature to afford the cyclized products, (3S)-3-alkyl-3,4-dihydro-1H-1,4-benzodiazepin-2,5-diones.
New conversion of Friendländer reaction of 3-amino-lH-benzo[f]chromene-2-carbonitriles with cyclohexanone
Jia Rong Li , Li Jun Zhang , Xi Quan Yang , Qing Li , Dong Wang , Chun Xia Wang , Da Xin Shi , Qi Zhang
2008, 19(1): 15-18  doi: 10.1016/j.cclet.2007.11.003
[Abstract](161) [FullText HTML] [PDF 361KB](0)
Abstract:
Two different skeletons of heterocyclic compounds, quinoline and quinazolinone analogs could be obtained by a novel one-pot synthesis from substituted 3-amino-lH-benzo[f]chromene-2-carbonitrile derivatives and cyclohexanone in DMF in the catalyst of anhydrous zinc chloride under reflux. A plausible mechanism was proposed.
Synthesis of tetracycline analogs and their bone affinities
Wen Cai Huang , Hu Zheng , Ling Ling Weng
2008, 19(1): 19-22  doi: 10.1016/j.cclet.2007.10.048
[Abstract](185) [FullText HTML] [PDF 253KB](0)
Abstract:
Tetracycline analogs were designed and synthesized and their bone affinities were tested on hydroxyapatite. The results showed that the carbonyl-amide-enol structure in A ring and phenol-ketone structure in BCD ring may be responsible for tetracycline's high bone affinity and either A ring or BCD ring has a planar conformation is essential.
Synthesis of antidepressant duloxetine via asymmetric transfer hydrogenation
Shan Zhen He , Xue Ming Li , Jia Dai , Ming Yan
2008, 19(1): 23-25  doi: 10.1016/j.cclet.2007.10.046
[Abstract](165) [FullText HTML] [PDF 251KB](0)
Abstract:
Antidepressant duloxetine (1) was prepared via asymmetric transfer hydrogenation of 3-(dimethylamino)-1-(thiophen-2-yl)propan-1-one (3). The Ru(Ⅱ), Rh(Ⅲ) and Ir(Ⅲ) complexes of several chiral ligands were examined as the catalyst and (S,S)-N-tosyl-1,2-diphenyl ethylenediamine (TsDPEN)-Ru(Ⅱ) complex was found to provide good yield and excellent enantios-electivity.
Synthesis and bioactivity of novel phthalimide derivatives
Tao Wang , Yi Hua Zhang , Hui Ji , Yan Ping Chen , Si Xun Peng
2008, 19(1): 26-28  doi: 10.1016/j.cclet.2007.10.049
[Abstract](164) [FullText HTML] [PDF 244KB](0)
Abstract:
Novel phthalimide derivatives (4a, 4b and 6a-6e) were designed as hybrids of thalidomide and NO-ASA, and their chemical synthesis and in vitro biological activities were presented. The preliminary results showed that compared to thalidomide 4a and 4b exhibited enhanced activities against ECV304 and HepG2 cells, whereas 6c was more potent against HepG2 cells.
Synthesis and in vitro cytotoxicity of novel 1,4-disubstituted phthalazines
Xin Zhai , Juan Li , Lei He , Su Zheng , Yao Bin Zhang , Ping Gong
2008, 19(1): 29-32  doi: 10.1016/j.cclet.2007.11.018
[Abstract](174) [FullText HTML] [PDF 244KB](0)
Abstract:
Eight novel 1,4-disubstituted phthalazines (7-14) were designed and synthesized. The structures of all the synthesized compounds were confirmed by IR, 1H NMR,13C NMR, MS and elemental analysis. Their in vitro cytotoxicity against cancer cell lines (Bel-7402 and HT-1080) were evaluated by standard MTT assay. Among them, compounds 9 and 11 exhibited more potentcytotoxicity than cisplatin.
Microwave assisted one-pot synthesis of novel molecular clefts with only one chiral arm based on deoxycholic acid
Bi Tao Zeng , Zhi Gang Zhao , Xing Li Liu , Yun Shi
2008, 19(1): 33-36  doi: 10.1016/j.cclet.2007.10.051
[Abstract](171) [FullText HTML] [PDF 267KB](0)
Abstract:
A rapid, safe, and efficient method for the synthesis of novel molecular clefts based" on deoxycholic acid was reported. Seven new molecular clefts have been synthesized in good yields (89-98%). This method proved to be extremely simple and highly efficient. The structures of these receptors were confirmed by 1H NMR, IR, MS spectra and elemental analysis.
1-[2-(2-Methoxyphenylthio) benzyl]-4-arylpiperazines derivatives: Synthesis and evaluation for dual 5-HT1A/SSRI activities
Xin Wang , Dong Zhi Liu , Ai Jun Li
2008, 19(1): 37-39  doi: 10.1016/j.cclet.2007.10.054
[Abstract](161) [FullText HTML] [PDF 234KB](0)
Abstract:
A series of 1-[2-(2-methoxyphenylthio) benzyl]-4-arylpiperazines derivatives was designed and synthesized based on 5-HT1A/SSRI drugs design strategies. The synthesized compounds were evaluated for their dual 5-HT1A/5-HTT activities.
1-(N-(2-(2-Methoxyphenylthio)benzyl)-N-methylamino-3-aryloxypropan-2-ols: Synthesis and evaluation for dual 5-HT1A/SSRI activities
Xin Wang , Dong Zhi Liu , Ai Jun Li
2008, 19(1): 40-42  doi: 10.1016/j.cclet.2007.11.020
[Abstract](168) [FullText HTML] [PDF 227KB](0)
Abstract:
A series of 1-(N-(2-(2-methoxypbenylthio)benzyl)-N-methylamino-3-aryloxypropan-2-ols derivatives were designed and synthesized based on 5-HT1A/SSRI drugs design strategies. The synthesized compounds were evaluated for their dual 5-HT1A/5-HTI" activities.
Synthesis and characterization of lower generation broom molecules
Jun Wang , Cui Qin Li , Shu Yan Zhang , Fang Sun , Teng Jie Ge
2008, 19(1): 43-46  doi: 10.1016/j.cclet.2007.11.009
[Abstract](167) [FullText HTML] [PDF 277KB](0)
Abstract:
Dendritic molecules with dodecyl groups as the hyperbranchs were synthesized in methanol by Michael addition with dodecylamine and methyl acrylate as raw materials. This new-type dendritic molecules were called vividly "broom molecules" in this report. The surface tension of the aqueous solution of broom molecule terminated amino group was measured by using the drop-volume method. The demulsification performance of the broom molecules for the oil/water (O/W) simulated crude oil emulsion was examined. The experimental results revealed that, as a new-type of surfactants, the broom molecules terminated amino groups showed demulsification for the O/W simulated crude oil emulsion.
Synthesis and characterization of α-N,N-dihydroxyethylaminopropyl-ω-butylpolydimethylsiloxanes
Yi Tao Yu , Qing Si Zhang , Meng Zhang , Hai Feng Sun
2008, 19(1): 47-50  doi: 10.1016/j.cclet.2007.11.022
[Abstract](163) [FullText HTML] [PDF 254KB](0)
Abstract:
A series of α-N,N-dihydroxyethylaminopropyl-ω-butylpolydimethylsiloxanes with different molecular weight were synthe-sized. The preparation included five steps which were hydroxyl protection, alkylation, anionic ring-opening polymerization, hydrosilylation and deprotection. The structure of reaction products was characterized by FF-IR, GC, 1H NMR.
Fe(NO3)3·9H2O/Fe(HSO4)3: An efficient reagent system for the oxidation of alcohols, thiols and sulfides in the absence of solvent
Farhad Shirini , Mohammad A. Zolfigol , Abdol-Reza Abri
2008, 19(1): 51-54  doi: 10.1016/j.cclet.2007.11.023
[Abstract](180) [FullText HTML] [PDF 250KB](1)
Abstract:
Fe(NO3)3·9H2O/Fe(HSO4)3 was used as an efficient reagent system for the oxidation of alcohols to their corresponding carbonyl compounds. All reactions were performed in the absence of solvent in good to high yields. Under the same reaction conditions, thiols and sulfides were also converted to their corresponding disulfides and sulfoxides, respectively.
Nitrosonium (NO+) catalyzed Michael addition of indoles to unsaturated enones
Guai Li Wu , Long Min Wu
2008, 19(1): 55-58  doi: 10.1016/j.cclet.2007.11.010
[Abstract](167) [FullText HTML] [PDF 302KB](1)
Abstract:
An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosoninm tetrafluoroborate in ethyl ether.
A novel synthetic route for 2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethanamine
Xiao Chuan Luo , Guo Hua Chen , Hui Bin Zhang , Wen Long Huang
2008, 19(1): 59-60  doi: 10.1016/j.cclet.2007.11.011
[Abstract](165) [FullText HTML] [PDF 221KB](0)
Abstract:
2-[2-(2,2,2-Trifluoroethoxy)phenoxy]ethanamine is the key intermediate of Silodosin, the α1-adrenoceptor antagonist for the treatment of benign prostatic hyperplasia. In order to obtain this intermediate, we developed a novel synthetic route by utilizing 2-nitrochlorobenzene as the starting material via O-alkylation, reduction, diazotization, acidolysis, etherification, condensation and hydrazinolysis. The highlight of this method lies on its convenience and economy in accessing this intermediate.
Two new flavanonol glycosides from Gordonia chrysandra
Kun Wang , Jing Zhi Yang , Li Zuo , Dong Ming Zhang
2008, 19(1): 61-64  doi: 10.1016/j.cclet.2007.10.033
[Abstract](170) [FullText HTML] [PDF 245KB](0)
Abstract:
Two new flavanonol glycosides named chrysandrosides A and B were isolated from the roots of Gordonia chrysandra Cowan. Their structures were determined by 1D and 2D NMR, FAB-MS techniques and chemical methods. Chrysandrosides A and B showed pronounced hepatoprotective activities against D-galactosamine (F-GalN)-induced toxicity in rat hepatic epithelial stem-like cells (WB-F344).
A new pyrrolidone derivative from Pistacia chinensis
Jian Jun Liu , Chang An Geng , Xi Kui Liu
2008, 19(1): 65-67  doi: 10.1016/j.cclet.2007.10.037
[Abstract](166) [FullText HTML] [PDF 251KB](0)
Abstract:
A new N-phenyl-pyrrolidone derivative had been isolated from Pistacia chinesis Bunge. Its structure was elucidated as 4-hydroxy-5-(2-oxo-1-pyrrolidinyl)-benzoic acid, named pistaciamide on the basis of the 1D-NMR, DEPT, HMQC and HMBC spectroscopic techniques.
A new alkaloid from Solanum cathayanum
Fan Cheng , Xiang Li , Jun Zhi Wang
2008, 19(1): 68-70  doi: 10.1016/j.cclet.2007.10.041
[Abstract](181) [FullText HTML] [PDF 230KB](0)
Abstract:
A new alkaloid compound 1 was obtained from Solanum cathayanum, a folk medicine of Hubei Province, together with a known alkaloid, orotic acid ethyl ester. On the basis of spectroscopic data and chemical methods, was identified as 8-hydroxy-3-methoxy-5H-pyrido[2,1-c]pyrazin-5-one. Compound can inhibit the production of NO in peritoneal macrophage of mice induced with LPS. The content of NO was determined by enzyme methods.
A new 8-O-4'-type neolignan from Ligularia narynensis
Xue Gao , Zhong Jian Jia
2008, 19(1): 71-72  doi: 10.1016/j.cclet.2007.10.039
[Abstract](168) [FullText HTML] [PDF 183KB](0)
Abstract:
A new 8-O-4'-type neolignan named narynenol (1) was isolated from the roots of Ligularia narynensis. Its structure and there lative configurations were confirmed by spectroscopic data interpretation.
Electrochemical determination of sulphide at multi-walled carbon nanotubes-dihexadecyl hydrogen phosphate composite film modified electrodes based on in situ synthesis of methylene blue
An Min Xiang , Li Zhou , Cheng Guo Hu , Sheng Shui Hu
2008, 19(1): 73-75  doi: 10.1016/j.cclet.2007.10.040
[Abstract](167) [FullText HTML] [PDF 181KB](0)
Abstract:
A novel electrochemical method for the determination of sulphide at a multi-walled carbon nanotube-dihexadecyl hydrogen phosphate composite film coated glassy carbon electrode (MWNTs-DHP/GCE) based on in situ synthesis of methylene blue (MB)was established.
Two new coumarin glucosides biosynthesized by transgenic hairy roots of Polygonum multiflorum
Rong Min Yu , Liang Bin Zhou , Chun Yan Yan , Guo Yan Duan , Yu Zhao
2008, 19(1): 76-78  doi: 10.1016/j.cclet.2007.10.047
[Abstract](169) [FullText HTML] [PDF 224KB](0)
Abstract:
The glycosylation of hydroxylcoumarin was investigated by using suspension cultures of hairy roots of Polygonum multiflorum, Two new coumarin glucosides (3 and 4) were biosysthesized by regioselectively glycosylation of corresponding substrates (1 and 2) in the system. The structures of two products were identified as 7-hydroxy-4-methylcoumarin 5-O-β-D-glucopyranoside and 7-hydroxy-3,4-dimethylcoumarin 5-O-β-D-glucopyranoside on the ground of chemical and spectroscopic methods, respectively.
A new dihydrobenzofuran lignanoside from Selaginella moellendorffii Hieron
Xiao Ke Zheng , Ke Ke Li , Yan Zhi Wang , Wei Sheng Feng
2008, 19(1): 79-81  doi: 10.1016/j.cclet.2007.11.019
[Abstract](161) [FullText HTML] [PDF 239KB](0)
Abstract:
A new lignanoside, (7R,8S)-7,8-dihydro-7-(4-hydroxy-3,5-dimethoxyphenyl)-1'-formyl-3'-methoxyl-8-hydroxymethylbenzo-furan-4-O-β-D-glucopyranoside (moellenoside A), was isolated from Selaginella moellendorffii Hieron. Its structure was determined by spectroscopic evidences.
A new C27-steroidal glycoside from Ophiopogon japonicus
Jian Zhong Wang , Li Ming Ye , Xiao Bing Chen
2008, 19(1): 82-84  doi: 10.1016/j.cclet.2007.10.055
[Abstract](158) [FullText HTML] [PDF 236KB](0)
Abstract:
A new C27-steroidal glycoside with three known compounds were isolated from the tuber of Ophiopogon japonicus (Thunb.) Ker-Gawl. Based on the spectral analysis, including HRMS,1H NMR,13C NMR, DEPT, 1H-1H COSY, HMQC and HMBC, their chemical structures were determined as pennogenin-3-O-α-α-rhamnopyranosyl-(1→2)-β-D-xyiopyranosyl-(1→4)-β-D-gluco-pyranoside (1), pennogenin-3-O-ct-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (2), ophiopojaponin C (3) and ophiopogonin D (4).
Ultrafast cyclic voltammetry with asymmetrical potential scan
Zhi Yong Guo , Xiang Qin Lin
2008, 19(1): 85-88  doi: 10.1016/j.cclet.2007.10.057
[Abstract](171) [FullText HTML] [PDF 651KB](0)
Abstract:
Based on the perfect ohmic drop compensation by online electronic positive feedback, ultrafast cyclic voltammetry with asymmetrical potential scan is achieved for the first time, with the reduction of anthracene acting as the test system. Compared with the traditional cyclic voltammetry utilizing symmetrical triangular waveform as the excitation one, the new method allows a simpler approach to mechanistic analysis of ultrafast chemical reactions coupled with a charge transfer. And perhaps more important, it alsoprovides a way to eliminate the interference of the adsorbed product in dynamic monitoring.
Rapid determination of atrazine in environmental water samples by a novel liquid phase microextraction
Qing Xiang Zhou , Guo Hong Xie , Long Pang
2008, 19(1): 89-91  doi: 10.1016/j.cclet.2007.10.036
[Abstract](168) [FullText HTML] [PDF 173KB](0)
Abstract:
A novel method was described for the rapid determination of atrazine using dispersive liquid phase microextraction in combination with high performance liquid chromatography (HPLC). Possible impact parameters such as sample pH, extraction and disperser solvents, salting-out effect, and extraction time were investigated. The experimental results indicated that proposed method possessed an excellent analytical performance. The linear range, detection limit, and precision (R.S.D.) were 0.1-50 ng mL-1 (R2=0.9955), 0.601 ng mL-1 and 6.4%, respectively. The proposed method was validated with the real water samples,and the spiked recoveries were in the range of 69.9-89.8%, respectively. These results indicated that the established method with high enrichment factor, short extraction time was an excellent alternative for the routine analysis of atrazine in environmental samples.
A novel spectrophotometric determination of copper(Ⅱ) with bromosulphonazo Ⅲ
Li Yuan , Shu Hui Huo , Xiao Na Ren , Hui Chen
2008, 19(1): 92-94  doi: 10.1016/j.cclet.2007.10.038
[Abstract](171) [FullText HTML] [PDF 294KB](0)
Abstract:
A novel ehromogenic reaction involving copper(Ⅱ) and bromosulphonazo Ⅲ (Br-SAZⅢ) in hexamethylenetetramine-hydrochloric buffer solution was investigated. The results showed that a blue complex of copper(Ⅱ) and bromosulphonazo Ⅲ was formed with a molar ratio of 1:1. The apparent molar absorptivity was 3.3×105Lmol-1cm-1 and the maximum absorption peak was at 616.8 nm. The proposed procedure was used for quantitative estimation of Cu(Ⅱ) inthe concentration range of 0-1.024 μg/mL with the detection limit (3σ) of 7.03×10-4 μg/mL (n=20). The relative standard deviations (RSDs) were 0.56-4,68%. Under the optimized conditions, total copper in the vegetables and tea was successfully determined.
Sensitive determination of fenpropathrin, cyhalothrin and deltamethrin in environmental water samples using multiwalled carbon nanotubes cartridge prior to HPLC
Qing Xiang Zhou , Guo Hong Xie , Jun Ping Xiao , Wei Dong Wang , Yu Jie Ding
2008, 19(1): 95-98  doi: 10.1016/j.cclet.2007.10.044
[Abstract](169) [FullText HTML] [PDF 215KB](0)
Abstract:
This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes (MWCNTs) cartridge. Important parameters, such as the sample pH, eluent and its volume, sample flow rate and sample volume were investigated in detail. The linear ranges, the detection limits, and precisions (R.S.D.) were in the range of 0.1-40 μg L-1 1.3-4.3 ng L-1 and 2.3-2.8%, respectively. The performance of the proposed method was validated with real water samples, and the spiked recoveries were in the range of 91.7-117.8%, respectively. The experimental results demonstrated that the proposed method was an excellent alternative for the routine analysis of such pollutants in environmental samples.
The synthesis and molecular recognization of the polyamine transporter of hydrazine-modified diamine conjugates
Jun Jun Zhou , Hao Huang , Song Qiang Xie , Yu Xia Wang , Jin Zhao , Chao Jie Wang
2008, 19(1): 99-101  doi: 10.1016/j.cclet.2007.10.031
[Abstract](169) [FullText HTML] [PDF 248KB](0)
Abstract:
A series of four novel hydrazine-modified diamine conjugates (7a-b, 8a-b) were synthesized and evaluated for cytotoxicity against Melanoma B 16, α-difluoromethylornithine (DFMO)-treated B 16, spermidine (SPD)-treated B 16, Mouse leukemia L 1210 and Hela cell lines. Both the DFMO-B 16 and SPD-B 16 experiments indicated that conjugates 7a-b and 8a-b could recognize the polyamine transporter (PAT) and enter the cells in part or in whole via PAT, although they were not as efficient as the reference, 9-anthracenemethyl homospermidine (1).
PEG-stabilized palladium nanoparticles: An efficient and recyclable catalyst for the selective hydrogenation of 1,5-cyclooctadiene in thermoregulated PEG biphase system
Tian Song Huang , Yan Hua Wang , Jing Yang Jiang , Zi Lin Jin
2008, 19(1): 102-104  doi: 10.1016/j.cclet.2007.10.042
[Abstract](152) [FullText HTML] [PDF 1010KB](0)
Abstract:
Polyethylene glycol (PEG)-stabilized palladium nanoparticles were prepared and applied to the selective hydrogenation of 1,5-cyclooctadiene (1,5-COD) in thermoregulated PEG biphase system, which allows a reaction in a single-phase at a higher temperature followed by a phase split at a lower temperature. Under the optimized reaction conditions, the conversion of 1,5-COD and the selectivity of cyclooctene (COE) were 100 and 98%, respectively. The catalyst could be easily separated from the product by phase separation and reused for 6 times without evident loss in activity and selectivity.
Phosphoryl choline-grafted water-soluble carbon nanotube
Tao Zhang , Kai Xi , Min Gu , Zheng Sheng Jiang
2008, 19(1): 105-109  doi: 10.1016/j.cclet.2007.10.002
[Abstract](173) [FullText HTML] [PDF 1021KB](0)
Abstract:
Water-soluble property is the precondition of biomedical evaluation and application of carbon nanotube (CNT). Novel watersoluble CNT was synthesized in this letter by grafting phosphoryi choline (PC) onto multi-wall CNTs. Utilizing FTIR, XPS, TGA and TEM, the title CNTs were characterized and it was found that the target products could facilely dissolve in water.
Self-diffusion coefficients of organic solvents in linear and branched high density polyethylene particles measured by PFG NMR
Xiao Wei Yan , Xiao Hong Ren , Siegfried Stapf , Jing Dai Wang , Yong Rong Yang
2008, 19(1): 110-114  doi: 10.1016/j.cclet.2007.10.034
[Abstract](179) [FullText HTML] [PDF 365KB](0)
Abstract:
Pulsed field gradient nuclear magnetic resonance (PFG NMR) has been performed to study the diffusion of organic solvents into semicrystalline polyethylene particles. Self-diffusion coefficients in different domains of the sample can be extracted through a bi-exponential fit to the echo intensity attenuation, which allows the precise determination of the tortuosity of the polyethylene particles. Further exploration comes from the measurements with branched polyethylene particles and it was found that the diffusion in polymer phase contributed significantly to the slow component of the exponential decay curve.
Effect of montmorillonite on kinetics of polyurethane preparation reaction
You Cao , Yu Jiang , Shu Lu Zhao , Xiao Jun Cai , Mei Long Hu , Bing Liao
2008, 19(1): 115-118  doi: 10.1016/j.cclet.2007.11.001
[Abstract](164) [FullText HTML] [PDF 394KB](0)
Abstract:
The prepolymerization and curing reaction kinetics of polyurethane/montmorillonite have been studied with end group analysis and FTIR respectively. It was found that the prepolymerization and curing reaction followed the 2nd-order kinetics. But the activation energy of prepolymerization increased from 42.7 k J/mol to 56.5 k J/mol after the montmorillonite was added in the reaction system, and activation energy of curing reaction decreased from 64.4 kJ/mol to 17.5 k J/mol.
Probing the weak interactions between amino acids and carbon monoxide
Ying Wu Lin , Chang Ming Nie , Li Fu Liao
2008, 19(1): 119-122  doi: 10.1016/j.cclet.2007.11.014
[Abstract](158) [FullText HTML] [PDF 306KB](0)
Abstract:
The relatively weak interactions between some non-charged amino acids with CO were investigated theoretically by using density functional theory (DFT) method. The stretching frequency of CO correlates well with its bond length followed the Badger's rule, and the correlation between binding energy and Mulliken charge partition of CO was also investigated for the first time.
Theoretical study of structural and electronic properties of oligo(thiophene-phenylene)s in comparison with oligothiophenes and oligophenylenes
H. Zgou , S. M. Bouzzine , S. Bouzakraoui , M. Hamidi , M. Bouachrine
2008, 19(1): 123-126  doi: 10.1016/j.cclet.2007.10.011
[Abstract](168) [FullText HTML] [PDF 655KB](0)
Abstract:
In this work, a quantum-chemical investigation on the structural and opto-electronic properties of oligo(thiophene-phenylene)(4TP) is carried out. The results are discussed in comparison with the properties of corresponding oligothiopbene (8T) and oligophenylene (8P). As the opto-elcctronic properties of this type of conducting polymers are governed by their electronic band gap, we shall also present a comparison among HOMO, LUMO and band gap energies of these three materials.
Address:Zhongguancun North First Street 2,100190 Beijing, PR China Tel: +86-010-82449177-888
Powered By info@rhhz.net